Hi
this is an upgrade offer over the phone. T mobile are offering £10/month loyalty discount if you upgrade your contract. I have upgraded my contract and got offered Combi 15 (300 minutes, unlimited texts) and Blackberry 8520 on 24month contract for £5 a month. (was also offered Nokia 6600i and T mobile pulse)
Total cost of the contract 24 months x £5= £120
Blackberry 8520 is worth around =£180+
this offer is not available online.
hope this helps somebody

called 150 from my contract mobile. As I said in the first post they will only offer £10 loyalty discount/month. BB 8900 is only available free from combi 25 package (hence offer would be £15 with discount).
here is the full list of all the T mobile monthly phone where you can see if they are available on combi15 or nothttps://www.t-mobile.co.uk/shop/mobile-phones/phones/pay-monthly/all/all/
hope this helps